Edge of Computing

EE Times

The IEEE has kicked off a new group to explore what comes after today’s emerging 40 and 100 Gbit/second versions of Ethernet. The 802.3 Ethernet Bandwidth Assessment Ad Hoc group is gathering data from a broad range of sources now and plans to submit a report by June 2012.

At least two camps have proposed very different futures for Ethernet to date. Companies such as Google and Facebook that run big data centers have called for Terabit Ethernet as early as 2013 to handle the growth of mobile and video data. Component companies have proposed a more realistic half-step to 400 Gbit/s.

"You are really seeing a division between suppliers and customers," said John D’Ambrosia who chairs the new ad hoc group. "Customers are going to have to go back and sharpen their pencils because we are running into the limits of physics," said D’Ambrosia, who is also a member of the CTO’s office at Force10 Networks.

Component designers claim the Terabit goal is unrealistic. The industry is currently focused on a relatively challenging move from 10 to 25 Gbit/s serial rates, and bundling more than about 16 lanes into one network is not practical, D’Ambrosia said.

Even academics are not yet engaged in exploring serial rates beyond 25G. Part of the impetus for defining 25Gbit products is to enable a new generation of 100G products based on four lanes of 25G each, reducing cost and complexity of the first-generation products that used ten 10G lanes.

The last major Ethernet standards effort, 802.3ba, was officially ratified in May 2010, defining both 40G and 100G data rates.

"It took some time for the group to reach consensus on doing both rates, and part of that was getting to an understanding of the needs for bandwidth," said D’Ambrosia who also chaired 802.3ba. "I learned my lesson once, and I don’t want to repeat that mistake," he said.

D’Ambrosia said he has been courting a wide range of sources to submit projections of their bandwidth needs to the new group including the New York Stock Exchange, carriers, Internet exchanges, R&D networks, content providers and the gaming community. "I would love to see a final report with multiple chapters representing each area."

In the meantime, engineers are working at full speed to enable a range of Ethernet capabilities using 25G serial signaling. They include a 100G Ethernet backplane and cabling effort also chaired by D’Ambrosia. Also in the works are new 100G standards for multimode and single-mode fibre optics expected to use 25G signaling.

"The industry is spending a lot of time and money on 25G right now," he said.

"We continue to see exponential broadband growth across the AT&T global IP backbone network, and appreciate the need for next-generation Ethernet standards to stay ahead of consumer demand," said Keith Cambron, president and chief executive officer of AT&T Labs, in a prepared statement.

Also in the statement: "It’s critical that Ethernet standards development keeps in front of the real-world needs of the marketplace so that network architectures are able to support growth in traffic without equivalent growth in operational costs and complexity," added Andrew Bach, senior vice president of communications and network infrastructure at NYSE Euronext.